Water

Facts About Water 97% of all water on the Earth exists within the oceans. 97% of all water on the Earth exists within the oceans. Of the 3% freshwater on the Earth, 68% of it is locked within glaciers. Of the 3% freshwater on the Earth, 68% of it is locked within glaciers. One out of 5 people in the world do not have access to clean drinking water One out of 5 people in the world do not have access to clean drinking water

Groundwater

Porosity Porosity is the measure of open (a.k.a. pore) spaces between rocks and/or sediment. Porosity is the measure of open (a.k.a. pore) spaces between rocks and/or sediment. The higher the porosity the easier water flows through rock. The higher the porosity the easier water flows through rock.

Permeability Permeability measures how fast water can flow through a rock. Permeability measures how fast water can flow through a rock. The more pore spaces that are connected to one another inside a rock, the higher its permeability is. The more pore spaces that are connected to one another inside a rock, the higher its permeability is.

Water Table

Aquifers Aquifers are layers of subsurface rock that contains water that can be pumped out. Aquifers are layers of subsurface rock that contains water that can be pumped out. Aquifers are the main source of water for humans, mainly for agriculture, industry, and drinking. Aquifers are the main source of water for humans, mainly for agriculture, industry, and drinking.

Watersheds A watershed is the area drained by a river system. A watershed is the area drained by a river system. A watershed contains both surface and groundwater. A watershed contains both surface and groundwater.

Wells Wells are holes that are dug below the water table where groundwater can be removed. Wells are holes that are dug below the water table where groundwater can be removed. As water is removed overtime, the aquifer can be depleted if removal of water is more that what is recharged. As water is removed overtime, the aquifer can be depleted if removal of water is more that what is recharged.

Wells Throughout History

Recharge Rates of Aquifers If groundwater is removed by humans faster than it is recharged by precipitation, the water table can begin to drop, causing wells to dry up. If groundwater is removed by humans faster than it is recharged by precipitation, the water table can begin to drop, causing wells to dry up. Large scale removal of groundwater for agricultural purposes poses a severe threat for areas where annual precipitation is low. Large scale removal of groundwater for agricultural purposes poses a severe threat for areas where annual precipitation is low.

Loss of Aquifers In the central plains of the United States, the Ogallala aquifer is decreasing in volume due to regional agriculture. In the central plains of the United States, the Ogallala aquifer is decreasing in volume due to regional agriculture. Took 2 to 6 million years to form. Took 2 to 6 million years to form. The aquifer is not recharged with the same volume that is extracted by humans for agriculture because annual precipitation is relatively low. The aquifer is not recharged with the same volume that is extracted by humans for agriculture because annual precipitation is relatively low.

Ogallala Aquifer In some areas of this aquifer, the water table is dropping at a rate of 1.7 feet/year. In some areas of this aquifer, the water table is dropping at a rate of 1.7 feet/year. The central plains of the U.S. is known as the country’s “bread basket” because of grain production. The central plains of the U.S. is known as the country’s “bread basket” because of grain production. Most croplands in the central plains are irrigated by the Ogallala aquifer. Most croplands in the central plains are irrigated by the Ogallala aquifer.

How Groundwater Flows The water table parallels the Earth’s surface. The water table parallels the Earth’s surface. Groundwater will flow downward in response to gravity. Groundwater will flow downward in response to gravity. The water table intersects at the edges of surface water (ex. lake, river, ocean) The water table intersects at the edges of surface water (ex. lake, river, ocean) The rate at which groundwater flows is slow, sometimes less than a centimeter per day. The rate at which groundwater flows is slow, sometimes less than a centimeter per day.

Point-Source versus Non Point-Source Pollution Point source pollution comes from a specific locations. Point source pollution comes from a specific locations. Examples include leaky underground tanks, factories, landfills, or industrial waste disposal sites. Examples include leaky underground tanks, factories, landfills, or industrial waste disposal sites. Non-Point Source Pollution comes from large areas where the pollutant’s location can not be specified. Non-Point Source Pollution comes from large areas where the pollutant’s location can not be specified. Examples include urban runoff and chemicals used as pesticides in agriculture. Examples include urban runoff and chemicals used as pesticides in agriculture.

Groundwater Pollution Groundwater can be polluted by the following sources: Biological: from bacteria or viruses Biological: from bacteria or viruses Inorganic substances: from metals, salts, or other chemical used in agriculture or industry Inorganic substances: from metals, salts, or other chemical used in agriculture or industry Pesticides and Herbicides: from agriculture or residential sources. Pesticides and Herbicides: from agriculture or residential sources. Organic Chemicals: by-products of industrial processes, gas stations, or septic tanks. Organic Chemicals: by-products of industrial processes, gas stations, or septic tanks. Radioactive Materials: Usually naturally occurring in granitic rocks. Radioactive Materials: Usually naturally occurring in granitic rocks.

Petroleum Based Fuels Gasoline can partially dissolve into water. Gasoline can partially dissolve into water. MTBE, a gasoline additive used to reduce air pollution in cars, can runoff gas station surfaces into groundwater. MTBE, a gasoline additive used to reduce air pollution in cars, can runoff gas station surfaces into groundwater. Research has shown that benzene and MTBE are known human carcinogens. Research has shown that benzene and MTBE are known human carcinogens.

Agriculture: Fertilizers and Pesticides Nitrates – Used in fertilizers, can kill infants under 6 months. Nitrates – Used in fertilizers, can kill infants under 6 months. DDT, a chemical now banned in the United States, was found to cause cancer in humans and weaken the shells to the eggs of birds. DDT, a chemical now banned in the United States, was found to cause cancer in humans and weaken the shells to the eggs of birds.

Heavy Metal Contamination Metals can be naturally occurring or by products of industry. Metals can be naturally occurring or by products of industry. Metals of concern include: Mercury, Arsenic, and Uranium. Metals of concern include: Mercury, Arsenic, and Uranium. Uranium is radioactive and can decay into Radon gas, which if breathed in can cause lung cancer. Uranium is radioactive and can decay into Radon gas, which if breathed in can cause lung cancer.

Measuring Groundwater Pollution A pollutant is usually measured in parts per billion (ppb), or part per million (ppm) A pollutant is usually measured in parts per billion (ppb), or part per million (ppm) Organizations such as the EPA determine the level of acceptable pollutant that is safe for humans or the local ecology. Organizations such as the EPA determine the level of acceptable pollutant that is safe for humans or the local ecology.